The 'Great Stupa' at Sanchi is the oldest stone structure in India and was originally commissioned by the emperor Ashoka the Great in the 3rd century BCE. Its nucleus was a simple hemispherical brick structure built over the relics of the Buddha. It was crowned by the chatra, a parasol-like structure symbolising high rank, which was intended to honour and shelter the relics. The construction work of this stupa was overseen by Ashoka's wife, Devi herself, who was the daughter of a merchant of Vidisha. Sanchi was also her birthplace as well as the venue of her and Ashoka's wedding. In the 1st century BCE, four elaborately carved toranas (ornamental gateways) and a balustrade encircling the entire structure were added.